In the wireless mobile communication terminal market with fierce competition, terminal manufacturers are committed to developing wireless mobile communication terminals comprising a plurality of wireless interfaces. These wireless interfaces establish wireless connections for example based on the Bluetooth wireless technique, the WLAN (wireless local area network) protocol, 2G (the 2nd generation network, like GSM—Global System for Mobile Communication), 2.5G (the 2.5-generation system, like GPRS—General Packet Radio Service), 3G (the 3rd generation system, like UMTS—Universal Mobile Telecommunication System) and the next generation data transfer protocol such as WiMax/Wibro and the like.
FIG. 1A depicts an exemplary configuration diagram of a multimode communication terminal in the prior art. The communication terminal 100A comprises three wireless interfaces, namely a Bluetooth interface 1100 dedicated to data communication based on the Bluetooth wireless technique, a WLAN interface 1200 dedicated to data communication according to the WLAN protocol, and a mobile communication interface 1300 dedicated to data communication according to the mobile communication protocol (e.g. GSM, GPRS, CDMA, etc.). Each of the interfaces comprises a baseband processor adapted to its own used protocol (i.e. comprising a Bluetooth baseband processor 1110, a WLAN baseband processor 1210 and a mobile communication baseband processor 1310, respectively), a clock module for providing a sample clock according to its own used protocol (i.e. comprising a Bluetooth clock 1120, a WLAN clock 1220 and a mobile communication clock 1320, respectively), an A/D and D/A converter for converting a signal from analog to digital and from digital to analog according to its respective clock signals (i.e. comprising an A/D and D/A converter 1130, an A/D and D/A converter 1230 and an A/D and D/A converter 1330, respectively), a RF processing module adapted to its own used protocol (i.e. comprising a Bluetooth RF processing module 1140, a WLAN RF processing module 1240 and a mobile communication RF processing module 1340, respectively), and an antenna adapted to the used protocol (i.e. comprising a Bluetooth antenna 1150, a WLAN antenna 1250 and a mobile communication antenna 1350, respectively). Due to the similarity in performed functions, the A/D and D/A converters, the RF processing modules and the antennas at respective wireless interfaces usually have similar or even the same physical structure. The difference is that depending on respective used protocols, they operate in different modes and accordingly have different operation characteristic parameters, such as RF central frequency, bandwidth, IF central frequency, baseband sample rate etc. As an example, FIG. 1 schematically depicts the main configuration of the RF processing modules at respective interfaces. They have the same configuration but operate on different frequency bands. For example, Bluetooth RF processing module 1140 operates on 2.402-2.408 GHz, whereas mobile communication RF processing module 1340 using CDMA2000-1x operates on 1.6 GHz. The configuration and operating principle of such RF processing modules are well known to those skilled in the art, and the detailed description thereof is omitted here.
According to the multimode communication terminal of the structure as depicted in FIG. 1, signals are independently received/transmitted and baseband processed via respective interfaces, and data to be received or transmitted is independently exchanged with an application processor 1000 which can start/cease the operation of one or more wireless interfaces according to user's commands or predetermined conditions.
To support higher-speed multimedia application, such as Mobile TV, it is required that the next generation mobile communication system using E3G/B3G/4G or the like and the next generation wireless system using WiFi or WiMAX or the like support orthogonal frequency division multiplexing (OFDM) and multi-input and multi-output (MIMO) techniques. In the MIMO technique, a plurality of antennas, i.e. an antenna array, can be used for communication transmission on both transmitter side and receiver side. If channels among respective transmitting/receiving antennas are independent of one another, a plurality of parallel spatial channels can be created using the spatial coherence or non-coherence of the antenna array. By transmitting data signals via these parallel spatial channels, signal-to-noise (SNR) will be enhanced significantly and data transmission rates will be increased.
However, in order to enable an antenna array with the MIMO technique on a multimode communication terminal, it is required that the communication terminal comprise more antennas, RF processing modules as well as A/D and D/A converters than those in the configuration depicted in FIG. 1A. This will give rise to the problem of cost and handset structure.
FIG. 1B depicts an exemplary configuration of a multimode communication terminal enabling an antenna array with the MIMO technique in the prior art. A communication terminal 100B comprises three wireless interfaces, namely Bluetooth interface 1100 dedicated to data communication based on the Bluetooth wireless technique, WLAN interface 1200 dedicated to data communication according to the WLAN protocol, and a mobile communication interface 1300B dedicated to data communication according to the mobile communication protocol. Among them, the mobile communication interface 1300B which uses the MIMO technique has an antenna array consisting of antennas 1350-1, 1350-2 and 1350-3, and in correspondence to respective antennas, mobile communication clocks 1320-1, 1320-2 and 1320-3, A/D and D/A converters 1330-1, 1330-2 and 1330-3 as well as mobile communication RF processing modules 1340-1, 1340-2 and 1340-3, to support three mobile communication parallel spatial channels. In mobile communication baseband processor 1310 are correspondingly added functional modules to process spatial signals, such as a spatial filter 1311 and a spatial signal analyzing module 1312 as depicted in FIG. 1B. In an operating state, the three parallel spatial channels formed by the antennas, the RF processing modules as well as the A/D and D/A converters receive/send data signals independently and synchronously (controlled by respective mobile communication clocks). The antennas, the mobile communication RF modules and the A/D and D/A converters respectively belonging to the three parallel spatial channels usually have consistent physical configuration and the same operation characteristics, such as RF central frequency, bandwidth, IF central frequency, baseband sample rate, etc.
Regarding to a wireless mobile communication terminal, good portability is usually necessary, i.e. the spatial size must be as small as possible. Additionally, both the manufacture cost and power supply belong to highly sensitive and key factors during design. On the existing wireless mobile communication terminal, only one RF channel with antenna will occupy ¼ to ⅓ of board area and will cost ⅕ to ¼ engineering bill of material (EBOM). Apparently, to manufacture a wireless mobile communication terminal according to the existing technical solution as depicted in FIG. 1B, the product spatial size will be necessarily increased so as to accommodate added RF channels of a corresponding antenna array. This will cause the increase of manufacture cost and the problem of conspicuous system power supply, which means such kind of multimode communication terminals can hardly meet the requirement in implementation and application and thus cannot occupy the wireless mobile communication terminal market with increasingly fierce competition.
To resolve this problem, a feasible method is to seek RF channel modules (including antennas, RF processing modules, clocks, A/D and D/A converters, etc.) with smaller size and higher integrity in order to reduce the board area of a single RF channel. However, the design of the existing RF channel modules is basically a well-developed technique and leaves little room for improvement. Moreover, even if the board area of a single RF channel is reduced by enhancing system integrity, the reduced margin is inadequate in relation to the expansion of spatial size caused by the several-fold increase of the number of RF channels.
Therefore, there is a need for a novel multimode communication terminal system architecture which enables the MIMO operation mode.